The present invention concerns a structured cosmetic material and a process for the production thereof and use thereof.
The field of cosmetics, in particular decorative cosmetics, frequently involves the use of structured materials which are spread over or rubbed into the skin or mucous membrane and which are intended to remain there for a prolonged period of time. Materials of that kind are used for example in the form of cream, gel, compressed powder or in stick form. The use of sticks is popular for decorative cosmetics, in particular for eyes and lips, for example in the form of lipsticks, eyebrow pencils, kohl eye pencils or eye-shadow pencils. For that purpose of use the material must be sufficiently firm to be able to form stick portions, but on the other hand it should be such that it can be well and properly applied and is to stay on for a long time without being sticky. Furthermore as far as possible it should also be water-resistant and should not irritate the skin. If the stick used is a rotational stick having a rotary mechanism into which the stick portion is fitted and projects unsupportedly therefrom, the material must also be of adequate strength.
There are already numerous compositions for the production of sticks. Thus for example stick materials are described and produced, which contain volatile solvents which evaporate at body temperature. The volatile solvent provides that the material can be easily applied. After evaporation of the solvent after application to the skin, the material has good adhesion to the skin. It will be noted however that in recent times the use of volatile solvents is undesirable for environmental reasons. It would therefore be desirable to provide a material which manages with water as a solvent.
Aqueous stick materials have already been described, which occur in the form of aqueous gels. For example WO97/17055 describes gel sticks which can contain a high proportion of water, but which must also contain at least 20% by weight of a water-soluble or water-dispersible gel-forming agent. Upon application, the high proportion of gel-forming agent gives a sticky, unpleasant feel.
DE 196 432 37 describes sticks which can have a water content of between 30 and 85% by weight. Here the stick material is produced in the form of a firm water/oil (w/o) emulsion. In those materials the aqueous phase is used to incorporate into a stick substances which are soluble in water but not in the fat phase. The products which are described here are however still not satisfactory as they are not stable at elevated temperatures and separate into the phases.
Therefore it is the object of the present invention to provide a cosmetic material which occurs in structured form, which can be processed to form sticks, which has good mechanical properties, which can absorb a large amount of water, which is extremely stable in respect of temperature, which is stable over a wide pH-range and is stable in terms of storage without change at up to about 60.degree. C. and which can be applied at up to 45.degree. C. The invention further seeks to provide that the cosmetic material is wipe-resistant but can easily be uniformly applied and is to give a good feel on the skin. In addition it is to afford materials enjoying good strong colours for decorative cosmetics.